According to Sharon Kleyne, the incidence of eye dehydration and dry eye has dramatically increased in the past 20 years and is becoming a global health crisis. Much of the increase can be attributed to environmental factors.

Environmental factors that could dehydrate the eyes and tear film could include:

Indoor conditions such as forced-air heating and cooling and insulated walls and windows.

Exposure to smoke, dust, wind, extreme heat and cold and other outdoor conditions could also contribute to eye dehydration.

A major contributor to eye dehydration is global climate change because the tear film obtains much of its water from the surrounding humidity in the air. In many areas, the air in becoming dryer and the humidity lower. This lowers the potential for hydration from the air and increases tear film water evaporation.

Even where the air is not dry, the humidity could be contaminated by air pollution, creating dehydrating and unhealthy conditions.